The new STXL cameras are the latest versions of the flagship STX series. The STXL is essentially the same camera design as the STX with three exceptions: First, the self-guiding CCD is moved from the main camera body to the new STXL filter wheel for guiding in front of filters; second, a rotating disk even-illumination shutter provides a shorter backfocus distance allowing the use of camera lenses; and third, the STXL uses the new STT remote guide head.
Two new STXL filter wheel options accompany the release of the STXL series camera. The Standard and Self-Guiding 8-position STXL filter wheels are of a similar design as the STT filter wheels They use the same precise positioning mechanism, but accommodate 50mm round unmounted filters. In the Self-Guiding model, the guiding CCD is incorporated into the filter wheel in front of the filters.
All of the other features of the STXL are the same as the STX series: Two-stage cooling to -60C, water cooling ready, ethernet and USB 2.0 computer interfaces, Several new innovations for serious imagers have been designed into this professional camera. To name a few:
• USB 2.0 and Ethernet in each camera
• Web browser control ready
• Two-Stage TE Cooling
• Minimum Cooling Delta -60 C with Air Only
• 12VDC operation (9-14VDC)
• Self-guiding in front of filters
• Full frame image buffer
• Continue guiding while downloading
• Internal and External Self-Guiding
• Optional Remote Guide Head
• Separate focus adjustment for built-in guider
• New photometric shutter for large arrays
• Variable speed fan
• Quick Disconnect Water Cooling Ready
• User Rechargeable Desiccant Plug
• Opto-isolated Relays for Telescope Control
• Tracking Relay LED Indicators
• Power Management LED Indicators
Self-Guiding in Front of Filters
It is well known that the advantage of easier guiding through a separate guide scopes is often limited by differential deflection of the guide scope relative to the main optical axis due to mechanical flexure or shifting of the mirror in the main OTA. It was this difficulty that SBIG addressed with our patented self-guiding design, and that we and others have addressed with an Off-Axis Guiding solution. Self-guiding is more convenient and more accurate, but can prove more difficult when narrowband filters are used. Previously, by piecing together an off-axis guiding system with parts from different manufacturers, users could place a guider in front of the filters, but this was generally more expensive, required additional equipment and did not always integrate well. Also, controlling two cameras might require one computer to run run two instances of camera control software. The ideal solution was therefore to design a self-guiding system that placed the guiding CCD in front of the filters using an integrated design that is easy to control. That is the new filter wheel / guider design of the STT and STXL cameras. The guiding CCD is built into the filter wheel and connects directly to the main cameras as an "external" tracking CCD. The optical design is optimized for guiding and all the commands and control of the guider are identical to those of our traditional self-guiding design. The guider does not require any power or control cables routed back to a computer and the system can be operated by a single software package as one camera.
Micron-Precision Filter Wheel
In addition, the STXL filter wheels are designed with the same precise positioning mechanism used in the STT design. With precise positioning, a filter is returned and held in precisely the same position every time it is rotated into the optical path, even after a loss of power and no matter how many times the filter wheel has moved. Our initial tests using the STT filter wheel measured this accuracy at better than 5 microns (less than one pixel). (See the STT filter wheel page for more information)
USB 2.0 and Ethernet Interface
The STXL series, like the STX and STT series cameras, has both USB 2.0 and Ethernet interface capability for the greatest versatility with a variety of computer systems. Users do not have to choose between the two. The Ethernet interface makes control of the camera over a network easy and less expensive than requiring a local computer to be controlled remotely. Moreover, the camera has a built-in web server. Also, with Ethernet, no camera drivers need to be installed. The STXL camera has a built-in web server that can be accessed from any browser. This also allows the use of a wireless network to be established for wireless control using an iPad or iPhone.
The STXL uses an innovative pin fin heat sink. This design is the most efficient for dissipating heat per given volume, and while it is more expensive than typical parallel fin heat sinks commonly round elsewhere, it provides superior performance and minimizes size and weight at the same time. This is one of the reasons the STXL camera weighs less than competing cameras with similar cooling performance. The new heat sink is an optimized design for this camera using a large custom pin fin heat sink mated directly to the hot side of the 2 stage TE cooler to achieve maximum heat dissipation with a single large fan. In less than 5 minutes the STXL-11000 achieves a delta of -60C using air cooling only.
Water Circulation Ready
While the design is aimed at sufficient cooling without water assist, it is possible to use water instead of air or in addition to air for optimum cooling. Using water instead of air will not require the use of a fan. Chilled water may also be used alone or with the fan for even greater cooling.
Since the early days of the original ST-7 camera, SBIG has been providing even-illumination shutters in our cameras, something not found in the majority of other cameras made for astrophotography. "Even-illumination" means that the shutter mechanism is designed to open and close in such a manner that it does not change the proportion of light falling on the sensor due to the shape or motion of the shutter itself. This is what one finds for instance with an iris type of shutter that opens-up starting at the center and closes over the center last.
User rechargeable desiccant
In order to allow the user the greatest flexibility in the field, and to avoid having to return the camera to the factory in order to purge the CCD chamber, we have designed the chamber to accept a rechargeable desiccant plug similar to our current ST and STL cameras.
Full Frame Image Buffer
The STXL series cameras have a full frame image buffer for storing image data during download. The STX will take an image during download process. We are exploring the possibility of using this buffer for pre-processing pixel defects based on a defect map provided by the CCD manufacturer, at the user's direction.
Variable Speed Fan
If the user desires air cooling only, the fan speed is controllable through software. Variable speed control allows the user to "tune" to fan to eliminate any resonance with the user's telescope thus suppressing harmonic vibrations.
I2C AUX Port
The STXL cameras has the same convenient I2C AUX port that we use on the STF and STT cameras for power and control of accessories such as filter wheels and Adaptive Optics.
Tracking Relay LED indicators
This handy set of 4 LEDs will tell you at a glance if the camera is issuing corrections to the mount in +X, -X, +Y or -Y directions during an imaging session.
The STXL will internally regulate a 12VDC supply so that the camera can be connected directly to any unregulated source such as a car battery. Four power LEDs indicate if the supply voltage drops to 11, 10 or 9 volts and when it is "good." Operation of the camera is possible with a supply voltage of 9.1 to 14 volts DC. Other LEDs indicate camera status and operation of the relays during guiding.
Remote guide Head
The STXL cameras supports a new remote guide head (see Accessory Section). This guide head plugs directly into the main camera and operates as an "external" tracking CCD. No additional connections to a computer are required.
|Manufacturer||Santa Barbara Instrument Group (SBIG)|
|CCD Class Available||Class 2|
|Computer Interface||USB 2.0|
|Cooling||Liquid Cooled - Optional, Thermo-electric Cooling (TEC)|
|Sensor Type||Kodak, Single Sensor|
|Software Features||CCDOPS, CCDSoftV5, TheSky v.5|